v6.0.0-ember-cli-flash: Prepare Release using 'release-plan' (#408)

Release (2025-03-04)

ember-cli-flash 6.0.0 (major)

💥 Breaking Change

• ember-cli-flash, test-app
  • #409 Modernise FlashMessagesService (@gilest)
  • #394 Convert FlashObject to native class (@gilest)
• ember-cli-flash
  • #410 Remove computed decorators from FlashMessage component (@gilest)

🚀 Enhancement

• ember-cli-flash
  • #411 fix: add type for spreaded FlashObject options (@charlesfries)

🏠 Internal

• test-app
  • #415 Upgrade test-app to v5 app blueprint (@gilest)

Committers: 2

• Charles Fries (@charlesfries)
• Giles Thompson (@gilest)